Java, using Groovy (Grails) during development just to be able to test code without recompiling?

Question

I do Java web development work using Spring MVC and basically I'm forced to do an Agile type of development where I have to make a lot of small changes and I sometimes end up wasting a lot of time having to compile each time I make a change ( I work for a start-up company and I am not given enough time to make unit tests, etc, this isn't ideal and I don't necessarily plan to stay with the company long-term but am just looking for ways to be more adaptable for the moment).

The app I'm working on needs to be fast and it does a lot of high volume data processing (its sort of a search engine but not a web search engine) so it has to be regular compiled Java for the production app but I'm wondering if I used Groovy with Grails, or something similar, for development if I could just write it as regular Java but then test code in real-time without having to recompile. I'm wondering how much effort would be involved in doing this as far as making it work then as compiled Java. Sorry if this is a newbie question I just am not sure where to look for info on this as most things about Grails seem more geared towards emulating scripting languages not what I am trying to use it for.

Answer 1

Agility is a state of mind, it doesn't have anything to do with a programming language or framework. I never have enough time NOT to do unit tests.

If you are coding in Java, code in Java, not in Groovy. Groovy is an (almost) superset of Java, so you could theoretically write your classes in Groovy and then compile them as Java, but this approach has a number of problems:

1) It's very easy to slip something in your code which isn't correct Java, closures are just SO useful :-) 2) Grails isn't easily translatable to Spring MVC, so you'd have to rewrite that bit as well.

So, I personally would not use Groovy/Grails.

When you say compile, do you really mean build the war and redeploy? Most IDEs (Eclipse, Intellij, etc) recompile a class as you save the file, so there is no delay. Assuming you're using such an IDE, you can run your (Tomcat) server from within Eclipse, and stuff gets automatically redeployed, and if necessary Tomcat restarts automatically.

If this still isn't fast enough, I recommend JRebel, which was so good that i forked out real money for a license. Using JRebel means that you (usually) don't even have to redeploy. You change a Java file in the IDE, and the change happens in your server without having to redeploy. I would highly recommend it.

One other thing I would do is to write unit tests for your code. You don't need to check them in, but they are a tool which will help your productivity.

Answer 2

What I would do here would be to embed groovy scripts within the java code as described here:

http://groovy.codehaus.org/Embedding+Groovy

In this way you can change your groovy code without the need to recompile. We've used this technique in our last legacy app that took 10-15 mins to recompile and install.

Groovy runs within the JVM and is dynamically compiled to bytecode, so there's no need to worry about the "production-ness" of it.